Agglutinant



Patented Jan. 11, 1938 PATENT OFFICE AGGLUTINANT Isidor Chesler, New York, N. Y., assignor to Eagle Pencil Company, a corporation of Delaware No Drawing. Application April 14, 1934, Serial No. 720,573

22 Claims.

While my present invention is more particularly concerned with agglutinating materials useful in various arts and of particular utility as the binder in the art of colored pencil or crayon leads or rods.

Among the objects of the invention are to provide an agglutinant useful for a lead or rod of the non-calcined type, which admits of making the same in any desired length, shape or color, including also black and white, of any desired hardness or softness, which imparts to the lead properties such that, even in small diameters it has tensile.

and shearing strength, as well as elasticity of high order, and admits of being sharpened to a point like ordinary graphite pencil leads and the strength and writing qualities of which are not adversely affected by the glue used for bonding the writing rod into a conventional wooden case.

Another object is to provide a binder for a pengo oil or crayon lead or rod of the above type, the use of which affords sufilcient penetrability to the lead to permit incorporation therein of waxy or fatty material or both, which determines certain of the writing qualities of the rod.

Another object is to provide an agglutinant more especially suitable as the binder of the lead or crayon-rod composition, which while contributing largely to the foregoing desired properties, is itself neither too horny nor tough, but wears readily and uniformly with the writing end of the pencil rod as the latter is consumed in use.

Another object is to provide an agglutinant or hinder of composite character including both a gummy mass acting as an adhesive binder, and

stringy particles acting mechanically primarly to reinforce the rod.

Another object is to provide an agglutinant or binder of the above character which will not pow-'- der or harden or otherwise deteriorate with age 40 to such extent as to impair its usefulness, and which requires no highly volatile nor inflammable solvents and thus obviates the expense and the danger due to the use of such solvents.

Other objects will be in part obvious and in part pointed out hereinafter.

According to the invention, the agglutinating materialis largely or wholly composed of etherized cellulose of solubility in water for example, to a degree less than that of completely methylated cellulose and to a degree greater than completely ethylated cellulose.

The preferred agglutinant or binder has a relatively high viscosity, suggesting in part at least a colloidal suspension rather than a true solution,

5 the agglutinant or binder being preferably not too readily water soluble, and not entirely dissolved in cold water.

Alkyl-ethers of cellulose wholly devoid of methyl radicals, as for instance, completely ethylated cellulose are, in general, substantially insol- 5 uble in water and the use of non-aqueous solvents, such as alcohol, glycerin, acetone or the like for preparing the paste for lead or crayon manufacture, in general, yields a product lumpy, brittle, hygroscopic or otherwise objectionable for prac- 10 tical purposes. Solubility in water generally increases with an increase of methyl radicals in the etherized cellulose, completely methylated or tri-methyl cellulose having maximum water solubility, and in solution presenting a substantialhr 15 homogeneous gummy substance from which a film having limited elasticity, resiliency and tensile strength may be formed, which while superior to gum tragacanth as a binder for lead and crayon rod compositions is inferior to the preferred 20 mixed ether of cellulose to be described hereinafter.

The preferred agglutinating material used for the purpose of this invention is not entirely homogeneous, for when thoroughly soaked in water, 25 there is present as insoluble or colloidal or colloided material, small portions of relatively insoluble or but partially soluble particles of a stringy character, disseminated throughout the mass. 30

The desired substance or hinder of non-homogeneous or heterogeneous character, in part gummy and in the dissolved state, and in part stringy and but partially or imperfectly dissolved, is composed preferably of mixed etherized cellulose, which 3 may, on the one hand be prepared as a physical admixture of diverse ethers of cellulose having the required diverse properties, or, on the other hand, may result from controlled etherificatipn with diverse radicals, of one and the same mass of 40 cellulose, which previously has been subjected to a mercerizing treatment.

A specific agglutinant or binder, according to I the invention, consists largely of di-methyl ethyl ether of cellulose, (that is, cellulose in which two 45 of the replaceable hydroxyls have been substituted by methyl group, and the other hydroxyl by ethyl group), substantially soluble in water, to yield the gummy medium, and this may or may not be admixed, depending upon the particular results 50 to be obtained in the finished products, with other ethers of cellulose, poorer or lacking in the methy radical and substantially insoluble in water, which constitutes the stringy ingredient of the binder.

Where as ordinarily preferred, it is desired to produce the mixed cellulose ether byone operation, in a single series of etherizing steps as in the formation, for instance, of an etherized cellulose containing both methyl and ethyl therein, as substituent groups, that is, a methyl-ethyl cellulose, purified cellulose, is treated with caustic soda, which operation mercerizes or renders the cellulose more susceptible to etherization, it being well known to those skilled in the art, that mercerized cellulose or alkalicellulose is more susceptible to etherification than is normal, original or unmodified cellulose. Thereupon the mercerized cellulose is etherized by treating with esters such as the chlorides or sulphates having the desired alkyl radicals. Preferably a mixture is used of like esters of methyl and of ethyl to produce the mixed methyl ethyl cellulose, as a mixture of dimethyl sulphate with diethyl sulphate.

While the above description may be sufficient to enable those skilled in the art to prepare the agglutinant or binder of the present invention, a detailed illustrative specification will now be given, to assure compliance with the statutory requirements.

An alkali-cellulose (soda cellulose) is first prepared from the purified .cellulose obtained, either purified wood pulp or purified cotton pulp and preferably of as high alphacellulose content :as possible, (such as the cellulose found most suitable for xanthating in the formation of viscose rayon) by treatment with sodium hydroxide solution of 18-20 per cent absolute NaOH or higher, for about 2 hours at 17-22 degrees C. The alkalicellulose is then shredded or otherwise subdivided into small particles, and then intimately admixed for several hours with finely powdered solid sodium hydroxide, 20 to 50 per cent of the weight of the original cellulose taken being employed, and as free from sodium carbonate and other impurities as possible. The length of time required, temperatures and concentrations for mixing are primarily dependent upon the solubility, viscosity and other physical characteristics desired in the final product. This finely divided mass is then placed in a pressure container, if

to be alkylated with a haloid ester as methyl chloride or ethyl chloride, or in an open container, if to be alkylated with a mixture of dimethyl sulphate and diethyl sulphate, either container being preferably provided with efficient stirring apparatus, and heated at from -140 degrees C. from one to four hours. The temperature of the reacting mass, after the addition of a proportion of methyl ester and ethyl ester, depends upon the degree of etherification, and the proportionof methyl to ethyl desired in the finished etherized cellulose. A desirable result is obtained by taking two parts by weight of the methyl ester to one part of the ethyl.

At the completion of the etherification step the mass is then precipitated, as by the addition of water or of brine, depending upon the degree of solubility in water of the etherized cellulose, or if methyl and ethyl chlorides are used as etherifying agents, the excess of alkyl chloride may be removedv by distillation. The crude mass is washed with brine or cold water to remove further amounts of reactants, if desired, and then dried at a comparatively low temperature.

The product after washing and drying'is, in general, a flocculent substance, which when treated with water assumes a fluid, gummy consistency, but is not entirely homogeneous, since it has distributed therein, the desired small stringy particles that are relatively unaffected or little affected by water. The gummy mass of the water-treated flocculent ether cellulose is probably largely di-methyl ethyl cellulose, which may have admixed therewith small proportions of trimethyl cellulose, and other bodies of a cellulosic etherized character. The stringy waterinsoluble particles are probably ethers of cellulose having not less than two ethyl radicals and probably having to some extent ethyl radicals substituted for all replaceable hydroxyls. The precise chemical composition of the agglutinant product is not known, but it seems probable that it consists of or contains various ethers of cellulose obtainable from the ingredients used, and that while most of the cellulose is completely etherized, a portion thereof is incompletely etherized. The stringy particles may in whole or in part be unetherized cellulose or other fiber. Preferably, the agglutinant after treatment with water has 15 to 25 per cent by weight of the insoluble, incompletely soluble or diflicultly soluble stringy ingredient therein.

The mixed ether cellulose of which the foregoing is a specific example may for present purposes consist of any of a relatively wide variety of ingredients, preferably, however, including some alkyl radical of lower order. Among the various ethers which serve for the purpose are mixed alkyl-cellulose, mixed alkyl-aryl cellulose, and mixed alkyl-aralkyl cellulose.

- While unlike, the other ethers of cellulose the aryl cellulose is not to applicants knowledge in commercial use at the present time, it is applicable for present purposes as herein set forth and as a chemical individual is known in the literature as appears from the following reference, A. Nastukofi, Journal of Russian Physical and Chemical Society, 1902, volume 39, pages 1109-35; Biochemisches Handlexikon, 1911, volume 2, page 232.

A preferred mixed alkyl-cellulose is the dimethyl-ethyl cellulose above described; an example of a mixed alkyl-aryl cellulose is di-methylphenyl cellulose; and of a mixed alkyl-aralkyl compound is di-methyl-benzyl cellulose. In each case, the bulk of the mixed cellulose ether is preferably to contain at least one and preferably two methyl radicals, in association with a member or members of one or more of other groups of radicals, including those enumerated above.

For a more complete understanding of a preferred application of the agglutinant, the structureand method of preparation of my new pencil and crayon rods therewith, will now be set forth.

According to the invention, the etherized cellulose to be used as agglutinant is soaked in water one or two days before use, preferably in a tinned copper vessel inert to the agglutinant.

The base mixture used for the lead or crayon composition comprises a filler such as ground china clay and a pigment such as milori blue ground wet, comminuted, filter pressed and air dried, and after admixturewith stearic acid and further crushing, admixed with calcium stearate and still further mixed. Thereupon the desired proportion of water soaked agglutinant is added, together with enough water to bring the mass to the desired consistency or plasticity. Experience has shown that a preferred moisture content, determinable by analysis of a specimen will range around 20 to 25 per cent.

The mixture of the batch is now ground, compressed and kneaded by use of a series of appropriate mills for securing a homogeneous intimately mixed and tough dough, which is thereupon hammered into cylinders and forced through perforated plates and re-compressed. Finally the dough is forced through dies of the proper calibre to produce the rod-like lead product. -In this operation, the stringy particles in the binder appear to become oriented substantially longitudinally of the rod and thus intermingled and intermeshed, thereby materially augmenting the mechanical strength of the product.

The lead rods are dried in racks according to familiar practice, including covering the leads with boards to prevent warping thereof, first at room temperature, then maintaining the leads for a week or more in a drying chamber at a temperature of 120 degrees F. or thereabouts, with the application of air in motion, until the moisture content of leads on test is found to be very low, whereupon the leads are cut to size.

The rod tightly compacted by the process above set forth develops or has therein minute pores,

. probably due to the escape therefrom of water evaporated in the drying operation. For all pur-. poses except where the rods are made with water a waxy nature, ordinarily equal parts of stearic acid and carnauba wax, preferably at a temperature of 180 to '190 degrees F. The dried rod has suilicient porosity to permit such melted waxy substances thoroughly to permeate the same, under the conditions of treatment, that is, to substantially fill all voids left in the rods by the evaporation of the water, and to fill the interstices in the stringy ingredient of the binder, a penetration attainable with much difllculty, if at all, where the lead has a case-hardened imperforate surface. The thorough wax impregnation results in a lead or crayon rod of excellent and uniform writing properties. After cooling, the leads are tested for strength, grade and quality and then preferably glued into the usual wooden sheaths.

The lead has tensile and shearing strength considerably greater than that of the best grades of leads of corresponding size at present on the market, and can be bent through a visible are before breaking.

The agglutinant when used as the binder for the leads of writing implements, is by no means limited in its application to colored crayons or pencils, but may be used for black leads or for white leads as well.

scribed an article and composition in which the several features of this invention are embodied,-

' and which article and composition in their action particles, distributed in said first portion.=

3. A physically and chemically heterogeneous agglutinating material comprising mixed partially etherized cellulose presenting in aqueous admixture, a carrier of water-soluble etherized cellulose, and small stringy particles therein of etherized cellulose. not entirely soluble in water,

said stringy ingredient being by weight substantially fifteen to twenty-five per cent of the mass. 4. A physically and chemically heterogeneous agglutinating material comprising a portion soluble in water and a portion incompletely soluble therein and in the form of small stringy particles distributed in said first portion and consisting largely of mixed etherized cellulose in which replaceable hydroxyls in cellulose have substituted therefor to different extents and distribution throughout the mass dissimilar radicals of the classes designated as alkyl, aryl and aralkyl.

5. A phylcally and chemically heterogeneous agglutinating material composed largely of mixed etherized'cellulose in which to diilerent extents and distribution throughout the mass methyl is partially substituted for replaceable hydroxyls in cellulose and in which a radical other than methyl is substituted for other replaceable hydroxyls, the whole forming an etherized cellulose partially soluble in water, and containing a portion stringy in character and not dissolving in water.

6. A physically and chemically heterogeneous agglutinating material comprising a portion soluble in water and a portion incompletely soluble therein and in the form of small stringy particles distributed in said first portion consisting of etherized cellulose in which all the replaceable hydroxyls have substituted therefor radicals to different extents and distribution throughout the mass at least two of which are dissimilar and of the classes designated as alkyl,aryl and arallwl.

7. A physically and chemically heterogeneous agglutinating material comprising a portion soluble in water and a portion incompletely soluble therein and in the form of small stringy particles distributed in said first portion and consisting of a cellulose product in which at least one of the hydroxyls is replaced by the methyl radical, and other hydroxyls have substituted therefor to different extents and distribution throughout the mass non-methyl radicals of the classes designated as alkyl, aryl and aralkyl.

8. A physically and chemically heterogeneous agglutinating material comprising alkylcellulose, having both methyl and ethyl radicals substituted for the replaceable hydroxyls of the origi- -nal cellulose the resultant product comprising a mixture of various ethyl and methyl compounds of cellulose presenting portions of greater and other portions of lesser solubility.

9. A physically and chemically heterogeneous agglutinating material of etherized cellulose including largely a gummy aqueous solution of suspension richer in methyl radicals and, having interspersed therein stringy, porous non-water soluble particles lower in methyl radicals.

10. A physically and chemically heterogeneous agglutinating material of etherized cellulose including largely a gummy aqueous solution or suspension in which methyl radicals are substituted for most of the replaceable hydroxyls, said solu-- tion or suspension having interspersed therein stringy capillary non-water soluble particles oi. ether cellulose low in methyl radicals.

11. A physically and chemically heterogeneous agglutinating material comprising mixed etherized cellulose presenting a water-soluble, gummy mass the major portion of methylated cellulose having distributed therein small stringy structures of etherized cellulose low in methyl radicals and relatively insoluble in water.

12. A physically and chemically heterogeneous agglutinating material comprising mixed etherized cellulose presenting a water-soluble, gummy mass essentially of methylated cellulose having distributed therein small stringy structures of etherized cellulose relatively insoluble in water, said insoluble particles having two or more radicals selected from the alkyl group, (other than methyl), the aryl and the aralkyl groups.

13. A physically and chemically heterogeneous agglutinating material of mixed alkyl aryl cellulose of a degree of etheriflcation such that a major portion is soluble in water and has interspersed therein stringy particles of ether incompletely soluble in water.

14. A physically and chemically heterogeneous agglutinating material of mixed alkyl aryl cellulose, incuding at least one methyl radical said material comprising stringy particles of ether incompletely soluble in .water interspersed in ether completely soluble in water.

v 15. A physically and chemically heterogeneous agglutinating material of mixed alkyl-aryl cellulose containing dimethylphenyl cellulose said material comprising stringy particles of ether incompletely soluble in water interspersed in ether completely soluble in water.

16. A physically and chemically heterogeneous agglutinating material of mixed alkyl-aryl cellulose essentially of dimethylphenyl cellulose said material comprising stringy particles of ether incompletely soluble in water interspersed in ether completely soluble in water.

17. A physically and chemically heterogeneous agglutinating material comprising'a mixed cellulose ether containing an aryl group and alkyl groups, including at least one methyl'group said agglutinating material of mixed alkyl-aralkyl cellulose containing dimethylbenzyl cellulose said material comprising stringy particles of ether incompletely soluble in water interspersed in ether completely soluble in water.

21. A physically and chemically heterogeneous agglutinating material of mixed alkyl-aralkyl celluose essentially of dimethylbenzyl cellulose said material comprising stringy particles of ether incompetely soluble in water interspersed in ether completely soluble in water.

22. A physically and chemically heterogeneous agglutinating substance comprising a mixed cellulose ether containing an aralkyl group and dissimilar alkyl groups including at least one methyl group said material comprising stringy particles of ether incompletely soluble in water interspersed in ether completely soluble in water.

ISIDOR CHESLER. 

